The present invention relates to a ductile pet chew having inclusions, preferably a tooth-cleaning component, and a method for forming the pet chew. In particular, the pet chew is formed from a ductile substrate material and either a fibrous component, a hard component, or both.
Pet chews have been known for quite some time. A pet chew is a product that is intended to occupy an animal that may, or may not, be consumed. In particular, some pet chews are food-like products, which may have some nutritional value, and are often intended to clean a animal""s teeth. Known pet chews are both hard and soft. Hard chews tend to be used in teeth cleaning by having the animal bite down on the chew to cause friction and to resultingly clean the teeth. Soft chews are intended to clean teeth and to occupy the animal""s time by having the animal gnaw on the pet chew for a sustained period of time. Dogs are known to enjoy the chewing of such products.
A variety of different products are used to make pet chews of varying hardness. For example, in the past, pet chews have been made from animal hide. Animal hide chews, however, have a number of disadvantages associated therewith. In particular, animal hide can produce a foul odor as a result of being chewed. Moistening, as a result of chewing, will cause the hide to soften and degrade, whereby the chews can smear and stain carpets and furniture. More problematic, the rawhide can swell and cause blockage in an animal. Additionally, the animal hide or raw hide can harbor bacteria, which can multiply in the mouth of an animal and be passed on to children, elderly people, or the immune impaired. As such, chews made from rawhide have been replaced by compositions that are xe2x80x9cman made,xe2x80x9d such as various starch and plastics based compositions.
Of the known developed compositions for use as an animal chew, most are either made from starch, protein, or mixtures thereof. Like the rawhide chews, the starch composition chews also have a number of problems associated therewith. Starch compositions are known to readily degrade in water, which means that during chewing, they become very xe2x80x9cmushyxe2x80x9d and can dissolve. Also, starch compositions readily dehydrates if left exposed to the environment for any length of time and resultantly can splinter or shatter. The crystalline nature of the starch polymers causes this shattering or splintering effect. Such splinters can poke or cut the animal and, thus, are undesired. For this reason, it is desired to have a chew that does not readily breakdown when moistened, or be prone to shatter when removed from its package and allowed to dry under ambient conditions. It is further desired to not have a chew that after moistening dries out and cracks.
Plastic or nylon animal chews do not suffer from degradation when exposed to moisture, nor do they dehydrate and readily splinter. However, plastic animal bones tend to be non-digestible, which is undesired. It is further believed that most consumers do not like the idea of having a animal consume synthetic plastic or petroleum-based products. As such, it is desired to have a chew that is perceived to be xe2x80x9cnatural.xe2x80x9d
Finally, other known animal chews are hard and brittle, which resultantly causes the chews to readily crumble. This type of chew is consumed quickly. Although these chews tend to be effective in cleaning teeth, they have a short-lived cleaning action. The duration of cleaning is directly tied to the length of time the crumbled material is in contact with the teeth. Thus, it is desired to have a animal chew that will not only clean teeth, but will have a cleaning action, which continues for an extended period of time.
It is preferably desired to have a chew that does not readily crumble, degrade in water, and does not pose a hazard by shattering or splintering. It is also preferred that the chew exhibit an extended duration of tooth-cleaning. Another preferred, but not required, characteristic, is that the chew be digestible. It is further preferred if the animal chew is made from natural materials, or at least perceived to be natural, and not made from synthetic or plastic materials.
The present invention relates to a pet chew composition formed from a polymeric material and an amount of inclusions. Specifically, the pet chew is ductile so that when chewed, an animal""s teeth will sink into the chew without tearing or breaking apart the composition. The ductility characteristics of the pet chew are important because this allows the chew to be held in contact with the animal""s teeth. A polymeric material is a composition that includes at least one polymer, and may include additional additives. Polymeric material, polymers, and substrate material will be used interchangeably throughout the present application. A polymer is a macro-molecule having five or more monomers.
As stated, included in the polymeric composition will be inclusion members. Preferably, the inclusions are either hard components or fibers. The inclusions are preferred for use in cleaning the animal""s teeth. Any of a variety of different types of fibrous materials may be used, including synthetic and natural fibers. The fibers, however, must have a length of greater than 900 microns. Any constituent can be used as a hard component, as long as it has a hardness greater than 0.5 Mahs. More preferably, the inclusion will have a hardness greater than 2.0 Mahs. Among the hard components that may be used with the present invention are various types of grains and legumes, as well as minerals and synthetic materials.
The polymeric material can be any of a variety of compositions, as long as it satisfies the ductility characteristics of the present invention, can retain the inclusions, and can be molded into any of a variety of different shapes or structures. It is most preferred if the polymeric material has a water activity of less than 0.9, and a total moisture content equal to or less than 25% by weight. It is also preferred if the polymeric material is edible. Most preferably, the polymeric material is either a starch or protein based composition.
Any of a variety of methods can be used to form the pet chew, as long as a chew composition of any of a variety of shapes and sizes may be formed. Among the suitable formation methods are injection molding, extrusion, rotary molding, compression molding, and sheet casting.
The present invention is advantageous for a number of reasons. In particular, the present invention is well suited for cleaning various animals"" teeth, because the fibers and hard inclusions are held in contact with the animal""s teeth during the chewing process. As such, a dual cleaning action is achieved because the ductile polymers rub against the teeth, and the inclusions contact the teeth. Additionally, the present invention is preferred because it is, preferably, digestible and does not significantly swell in the stomach of an animal. The present invention does not readily break down due to exposure to moisture, and, therefore, does not stain or damage furniture or carpets.
The present invention relates to a pet chew composition formed from a substrate material and an amount of an inclusion component, wherein the pet chew is ductile so that an animal""s teeth, in particular, a dog""s teeth, can penetrate into the chew. The inclusion is preferably a tooth-cleaning component. The chew is such that it does not readily crumble, break, or tear, but requires multiple chews or compressions to break down. Importantly, the ductile character of the chew causes the tooth-cleaning components to be held in contact with the animal""s teeth. This results in a cleaning action of the animal""s teeth, which is superior to the rubbing action of the ductile material alone. The substrate can be any of a variety of materials that are ductile as described herein. The tooth-cleaning constituents should be somewhat abrasive and hard to thereby rub tarter off of the animal""s teeth and to resultingly clean the teeth. The present invention also relates to a method for producing the pet chew.
The composition of the chew is such that it contains inclusions, preferably, hard components, or fibrous components which, when rubbed against the animal""s teeth, will result in a cleaning effect. The substrate composition used to form the pet chew can be any of a variety of constituents, as long as the pet chew is ductile and can readily hold the inclusions. The inclusions or compound will work in conjunction with the ductile substrate material to perform as a tooth-cleaning component or components. As stated, it is necessary for the substrate composition, which is used to form the pet chew, to have a ductile quality. Ductility is defined as a cohesive material whose shape can be modified under force or after being stretched, and has a propensity to return to its original shape, while also showing resistance to fracturing. Such ductility also causes the tooth-cleaning components to be held in contact with the animal""s teeth, while the teeth rub on the substrate composition, or as the teeth penetrate the substrate composition. In particular, the substrate should be such that the animal""s teeth will penetrate the pet chew so that one or more of the teeth, or a portion of the teeth, are temporarily surrounded by or slightly penetrate the chew. Once the teeth are removed from the chew, it should return to its original shape, or to a shape substantially similar thereto. Any of a variety of substrate materials may be selected. Most preferably, the substrate is a polymeric material.
Ductility is not directly quantified by any sort of measurement but is, instead, quantified by a cumulative measurement of the tensile strength, flexular strength, shear strength, hardness, and penetration characteristics of a composition (the pet chew). As such, it is preferred for the finished polymeric composition or substrate to have a tensile strength ranging between 200 psi and 1050 psi. More preferably, the composition will have a tensile strength equal to between 200 psi and 750 psi. Flexular strength of the composition should range between 3 lbs. and 75 lbs., which causes a xc2xd inch deflection. The shear strength should range between 80 lbs. and 175 lbs. The hardness of the composition should measure between 68 and 90 rockwell. The penetration characteristics of the polymeric composition should measure between 2 lbs. and 28 lbs. The above measurements are derived using the methods disclosed in Example 6 herein.
The particular characteristics of the chew can be controlled such that the ductility characteristics can be changed based on the desired finished characteristics. As a result of the wide variations in chewing aggressiveness between different animals and breeds of animals, it is desired to have a range of ductile characteristics. It is also desired for the consumable chews to be such that ductile characteristics can be changed to provide for various chew durations by a typical animal. Thus, the chew can be constructed such that it has a greater or shorter longevity dependant upon the desired final use.
It is preferred, but not required, that the polymeric material is edible and digestible by the animal, and does not readily degrade in water. The polymeric material should also be capable of being formed into a desired shape. This can be accomplished through injection molding or an extrusion process, as well as a co-extrusion process. Finally, it is necessary for the polymeric material to be such that it readily retains and holds various inclusions, especially tooth-cleaning components, such as fibers and hard components.
Suitable polymeric materials for use in forming the pet chew can be selected from protein polymers, starch polymers, plastic polymers, rubber, non-digestible natural products, and other human-made materials (including nylon, polyester, and polylactic acid), and combinations thereof. The polymer or polymeric material will be comprised of at least one type of polymer, and will include additives, such as flavors, plasticizers, and preservatives. It is most preferred to use a polymer made from either a protein polymer, a starch polymer, or combinations thereof, because these tend to be consumable and are considered natural by pet owners. Such polymers are, typically, readily digestible by an animal. Polymers high in protein are preferred for use if it is desired to form a chew that does not breakdown, soften, or dissolve in water. The protein polymers may be derived from protein fractions found in wheat, soy, corn, barley, and other types of seeds, vegetables, or plants. A preferred protein is derived from wheat. Starch compositions are typically used for pet treats or chews exhibiting short chew lives or chews intended to be very hard. Although there are a variety of starch types and sources for starch, a preferred starch is one that is not chemically modified and contains significant levels of amyl pectin. A preferred source would come from the group consisting of wheat, tapioca, corn, rice, maize, potato, other plant starches, or blends thereof. Also, carbohydrates, other than starches, may be used. It should be noted that chemical and physical modifications of the polymer of polymer base can improve ductile characteristics.
In order to ensure that the polymeric material has sufficient ductility, it is often required to add a softener, or plasticizer, constituent. A preferred plasticizer is a humectant that binds water. Any of a variety of other plasticizers, however, may be used, as long as the resultant polymeric material has the above-mentioned characteristics. Typically, the plasticizer constituent will be added to the polymeric material in an amount equal to between about 10% and 65% by weight of the polymeric or substrate material. This amount may vary, however, dependent upon the particular polymeric material, the particular plasticizer, and the desired finished characteristics of the chew. As before, it is preferred if the plasticizer is readily digestible by the animal, or passes through the animal with no ill side effects.
A variety of different materials may be used as inclusion components found in the pet chew. The inclusions, preferably work with the polymer to clean teeth, and may be either a fibrous component, a hard component, or mixtures thereof.
Any of a variety of fibrous materials may be used, as long as the fibrous materials have a length of at least 900 microns. More preferably, the fibers will have a length of at least 1,000 microns. Even more preferred, is a length ranging between 1,800 microns and 2,500 microns. The stated length of the fiber is necessary, as this has been found to be the most preferred way to provide improved cleaning action of the animal""s teeth. Any of a variety of fibrous materials may be used, including cellulose, sisal, cotton, and any of a variety of synthetic fibers. The synthetic fibers include polyester, nylon, olefin, and any other synthetic fiber. As before, it is preferred if the fibrous material is of a natural origin. The fibers can be added in an amount equal to between 1% and 15% by weight of the polymeric material. Preferably, the fibers are added in an amount equal to between 4% and 8% by weight of the polymeric material.
Any of a variety of hard particles, or particulates, may be used as inclusions and teeth cleaning components. In general, the hard particle materials will scrape against the tooth of the animal and, thereby, remove tartar and clean the animal""s teeth. A variety of different synthetic, natural, and manufactured hard particle materials may be used. As before, it is most preferred if the hard particle materials are of a natural origin, or made from natural materials. Thus, the most preferred hard components are selected from the group consisting of whole or broken dried cereal grains and legumes, such as rice, wheat, oats, corn, soybeans, peas, and other particulates. The hard particles are added in an amount equal to between 5% and 45% by weight of the substrate material. The particles are more preferably added in an amount equal to between 10% and 35% by weight of the substrate material. Even more preferably, the particles are added in an amount equal to between 15% and 25%. The particles should range in size from between 2 mmxc3x975 mm to 400 mesh or 37 microns. The particles will have a hardness of at least 0.5 Mahs and, more preferably, between 2.0 and 9.0 Mahs. Optionally, various mineral powders may be used with the present invention.
The resultant pet chew will be comprised of between 50% and 95% by weight of polymeric material, more preferably 70% and 90% by weight. Polymeric material means the polymer or polymers that form the chew, as well as the additives, except for the fibers and inclusions. Preferably, the pet chew will have a water activity level equal to or less than 0.9, and a moisture content equal to or less than 25% by weight.
To form the pet chew, there are two preferred processes for melting the polymeric material and shaping it, depending on the desired shape and appearance. Injection molding is used for a more three dimensional shape, while extrusion is used for co-extrusion, or two dimensional shape. Such injection molded shapes include bone-shaped, pet treat-shaped, and toy-shaped structures, and those shapes made by extrusion processes, which include cookie-type shapes, bar-type shapes, and multi-textured, colored, or flavored shapes. Generally, the temperature for melting the starch or protein polymeric material will range between 155xc2x0 F. and 210xc2x0 F. For polymeric materials high in protein, it is necessary to thermal set the pet chew after shaping. This can be accomplished by heating with hot air, steam, or ionized energy. Other methods for thermal setting extruded pet chews include dipping in hot oil or boiling water. Preferably, the chews are cured after extrusion. This includes thermal settings and drying. An alternative to extruding the chews is to injection mold the polymeric material.
In the alternative, a leavening agent or gas producing compound can be added, such as a bicarbonate.
The following examples are for illustrative purposes only and are not to be construed as limiting the scope of the subject invention.